Anti-deflection doctor



April 30, 1963 R. s. wAsHBURN 3,087,185

ANTI-DEFLECTION DOCTOR Filed Feb. 15, 1961 2 Sheets-Sheet 1 61x BY ATTORNE April 30, 1963 R. s. WASHBURN 3,087,185

ANTI-DEFLECTION DOCTOR Filed Feb. 13, 1961 2 Sheets-Sheet 2 ATTORNEY United States Patent iifice 3,087,185 Patented Apr. 30, 1963 This invention relates to an assembly for mounting a doctor blade adapted to cooperate with a traveling surface, and more particularly, for an assembly for mounting a doctor blade adapted to cooperate with a roll in a paper machine or similar apparatus involving substantial machine width.

Although the instant invention may have use in a number of fields, it is particularly useful in the paper making art, wherein ythe machinery involved has substantial width (in the cross machine direction as contrasted to the machine direction or longitudinal direction of the material being processed in the machine). `In a paper machine, for example, sheets of very substantial width are handled in a number of different devices, many of which involve equipment such as rolls and/or cross beams which are supported at their ends (beyond the edges of the paper sheet), so as to result in a certain amount of beam deection -in the central portion in response to the load. Such deiiection may be quite nominal numerically but it is often extremely significant from an operation point of view. The load of a given cross beam or roll subject to deflection in such a machine includes the weight of the earn or roll itself plus any of a number of different forces which may be applied to the roll or beam generally normal to the centroidal axis thereof. Numerous efforts have been made by prior workers in the art to correct or Compensate for the tendency for deflection in the axes of rolls used in paper machines.

The instant invention is addressed to the problem of constructing a suitable anti-deection doctor assembly. In general, the doctor comprises a doctor blade (supported by a doctor back) which is mounted in close running relation or in actual Contact with a traveling surface such as the roll surface. The doctor blade is generally coextensive with the roll, i.e. extending substantially from one end to the other of the (full paper machine width of) the operating surface of the rotating roll. The doctor is used on breast rolls to remove water therefrom, on press rolls to remove paper and ber therefrom, on dried rolls to remove paper and possibly pitch or similar deposits, on calender rolls to remove paper or fibrous particles, etc. In the ideal arrangement the doctor blade maintains a substantially straight theoretical line of contact with respect to the roll surface, whereat the doctor blade actually contacts the roll surface or it may be in substantially uniformly spaced very close running relation thereto. This so-called line of contact is ideally a straight line on the surface of the roll that is parallel to the axis of the roll. A difficulty which has been encountered in the prior art is that the doctor back itself carrying the blade has substantial weight and, being supported also only at its ends, tends to deflect centrally. Such deflection, in turn, tends to impart a curve to the leading or operating edge of the doctor blade and thus to the line of contact with the roll. In addition, many rolls in a paper machine may be operated with a slight crown or other non-uniform surface contour, so that the operating line of Contact is not an exactly straight line. The prior workers in the art have attempted to solve these and related diiiculties by correcting or revising the doctor back mounting for the doctor blade (with shims or otherwise) so as to compensate for the general deflection of the doctor back and also to obtain the desired specific contour for the leading or operating edge of the doctor blade for a given set of operating conditions.

The instant invention affords an improved mounting assembly for the doctor blade wherein simplified and unique means are provided for compensating to a substantial extent for the tendency of the doctor back or any cross beam Vto deflect under the operating load. The instant invention also provides a unique arrangement for maintenance of the desired contour of the leading edge of the doctor blade during variations in a number of operating conditions, in-

cluding the operating temperatures of the roll and doctor blade land the pressures at which the doctor blade may be urged against the roll. In addition, the instant invention affords an improved mounting means for the doctor blade to compensate for vibration per se in the doctor blade during operation and the tendency of such vibration to cause undesirable side effects in the operation including failure of the doctor blade to retain the desired alignment with respect to the roll.

It is, therefore, an important object of the instant invention to provide an improved assembly for mounting a doctor blade, and apparatus comprising the same.

It is ranother object of the instant 'invention to provide an improved doctor blade mounting which is capable of compensating for variations in operating :conditions including operating temperatures and pressures with respect to the blade and roll associated therewith.

Yet another object of the instant invention is to provide an improved doctor blade mounting that is adapted to avoid harmful effects resulting from vibration incidental to the operation of the doctor blade.

Still another object of the -instant invention is to provide an assembly for mounting a doctor blade adapted to cooperate with the traveling surface, which comprises a doctor back for -carrying the doctor blade, a cross beam c0- extensive with said doctor back, and allochiral mounting means positioned intermediate'the central portion of said doctor back and each of the end thereof forsupporting the load of said doctor back on said cross beam.

An additional object of the instant invention'is to provide an improved apparatus comprising a roll mounted for rotation, a doctor blade urged into cooperative relationship with said roll and extending substantially from lone end of the roll to the other, a doctor back coextensive with said blade and carrying the same, a cross beam received by said doctor back and coextensive therewith, mounting means positioned inwardly from the ends of said doctor back at approximately the quarterpoints thereof carrying the load of the doctor back on said cross beam, means rotatably mounting the opposite ends of said cross beam and carrying the load thereof, and means for r0- tating said cross beam thereby to urge said-doctor blade against said roll.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is essentially a top plan view of a doctor assembly of the prior art;

FIGURE 2 is essentially an elevational view of the doctor assembly of FIGURE l with the doctor back shown in section and parts shown schematically;

FIGURE 3 is an essentially diagrammatic view showing in exaggerated manner deflection curves obtainable in the prior art devices;

FIGURE 4 is an essentially schematic end elevational View of the. doctor assembly of FIGURES l and 2 taken from the left hand side of FIGURE 2;

FIGURE 5 is an essentially top kplan View of an antideiiection doctor assembly of the invention;

FIGURE 6 is a front elevational view of the doctor assembly of FIGURE 5, with parts shown"schematically and parts shown in section;

, the points of support (ite. the bearings 13b, 13e).

FIGURE 7 is an essentially diagrammatic view showing deflection curves obtained under one set of conditions in the practice of the instant invention;

FIGURE 8 is an essentially diagrammatic view show- -ing deflection curves obtained under a different set of conditions in the practice of the instant invention;

FIGURE 9 is an enlarged fragmentary sectional detail view taken of the region designated IX in the View of FIGURE 6; and

FIGURE 10` is an essentially diagrammatic end elevational view taken along the left hand side of FIGURE 6.

As shown on the drawings:

In FIGURES l, 2 and 4, there is shown a roll \10 mounted for rotation with an operating peripheral surface 10a cooperating with a doctor blade 11 of the prior art. The doctor blade 11 operatively cooperates with the roll surface lfm along a line of contact L-11, here indicated as being in actual contact with the leading edge '11a of the doctor 11. In this arrangement the leading edge 11a of the doctor 11 is just touching the roll surface 10u (along the line L-11) `and in order to obtain perfectly satisfactory operation the leading edge 11a must touc the roll surface 10a with substantially the same pressure and Ialong a substantially straight line L-11 from substantially one end '10b to the other end 16C of the roll 10 (which in this embodiment has a substantially flat uncrowned operating surface lila).

The doctor blade 11 is mounted by conventional means on a forwardly extending lip 12o of a conventional doctor back 12 which is here indicated as -a box beam. The doctor back 12 is provided with right and left hand (i.e. allochiral) stub shafts 12C and 12b, respectively, which are rotatably mounted in bearings 13b and 13C, respectively. The bearings 13b yand 13C rotatably mount the opposite ends (i.e. stub shafts 12b and 12C) of the doctor back 12 and carry the entire load thereof (via fixed supports S, S mounting bearings 13b and 13e) The load of the doctor back 12 is primarly the rather substantial weight of the doctor back 12 itself, plus the relatively lesser weight of the doctor blade 11 and a Variable force in response to the pressure at which the doctor blade 11 is urged against the roll 10. As indicated in FIGURE 3, this overall load results in a central downward deection from the theoretical center line C-11 of ythe unloaded doctor back along a dashed line D-11 which is shown to deviate in exaggerated manner from the center line C41. The deflection of the central axis C41 (which is also approximately the axis of rotation) along the line D-11 is actually quite small numerically, but it would be extremely significant from an operating point of view for the reason that a doctor blade 11 mounted on the lip .12a of the doctor back 12 would be deiiected correspondingly so that its leading edge 11a (having a deflection corresponding to the line D-11) would not be contoured to conform exactly with the theoretical line of `Contact L-11. It will be appreciated that in the present situation Where the leading edge 11a is actually touching the line of contact L41, such deflection would not necessarilycause an appreciable deviation from the line of contact L-11 by the leading edge 11a, but it would cause uneven pressures and wearing along the line of contact L-ll, plus uneven flexing of the doctor blade 11 and other undesirable features. It will further be appreciated that the doctor back 12 is represented here as having merely a box beam structure, and numerous other structures have been suggested in the art for strengthening the doctor back, but in any event there is some deliection by virtue of the -substantial weights involved and the substantial cross machine dimension of the doctor back 12 between The workers in the prior art have recognized that such deflection is inherent in the doctor back 12 and they have machined contour of the doctor lblade `11 and/ or doctor back lip 12a, machined contour of the leading edge 11a of the doctor blade, etc. Although many of these solutions to the yproblem are complicated and expensive, they make possible the substantial alignment of the leading edge 11a in conformance with the desired line of contact llc-11, which in the diagram of FIGURE 3 would involve parallel alignment with the theoretical center line C-11. These prior art methods, however, involve a suitable positioning of the leading edge 11a for a predetermined set of operating conditions.

For example, if we assume that the actual deflection of the doctor back 12 conforms with the dashed line D-11 in FIGURE 3 at a given operating temperature and the doctor blade l11 has been mounted in corrected position on the doctor back 12 so that the leading edge 11a conforms substantially with or is parallel to the theoretical center line C-11, then we have correct alignment for a given set of operating conditions. If, however, the operation of the device involves substantial heating of the doctor back 12, it will be appreciated that the doctor back 12 will expand (in a manner corresponding to its coefficient of thermal expansion), so that the deection of its central axis may be increased to conform approximately with the short dashed line T-11 of FIGURE 3 (again showing the deflection in exaggerated manner). The machining of the doctor blade or shim mounting thereof is not, of course, adapted to compensate for this change in deflection curves from D-tl lto T511.

It will also be noted that the doctor back 12 is equipped with means for effecting limited rotation thereof in the form of allochiral shafts fob and 16C connected to head members 17h and 17C on the stub shafts 12b and 12C, respectively, the shafts or lever arms 16!) and c are each equipped with adjustable actuating means in the form of diaphragm actuators 181') and 18C. As indicated in FIGURE 4, wherein the diaphragm element b is shown diagrammatically, upward movement of the diaphragm actuator 18!) elfects rotation of the stub shaft 12b about the centroidal axis C-11 which, in turn, urges the doctor blade leading edge 11a against the line of contact L-11 with greater force. The roll 12 itself resists this force along the line L-11, so that the doctor blade 11, the doctor back lip 12a and the doctor back 12 itself may then function as if they were loaded in a direction substantially opposite to the weight load of the doctor back 12. In this situation, it will be appreciated that the doctor blade 11 and mounting lip 12a may tend to function as a beam subjected to a load from beneath so as to cause a central upward deflection indicated in exaggerated manner in the dot-dash line U-11 in FIGURE 3. In this respect, it will be appreciated that such upward force will be resisted to the greater extent along the right and left hand edges of the doctor back assembly in the proximity of the allochiral lever arms 16h and 16C; but the effect of the force couple applied to the stub shafts 12b and 12C via the lever arms 16h and 16e is less in the central portion of the doctor back (remote from the stub shafts 12b and 12C) than it is at the stub shafts 12b and 12C. Also, another variable is introduced into the force system here by Virtue of the fact that, although the theoretical line of contact L-11 remains fixed and substantially straight throughout the length of the doctor back 12, the force couple exerted via the lever arms 15b and 16C actually functions through points of revolution at varying distances fro-m the line of contact L-11, because such points are located on an axis of rotation which may conform with the line of deflection D11, rather than the true center line C-11 which is parallel with the line of contact L-11. In other words, the force couple urging the leading edge 11a down along the left hand side of the doctor back via the left hand lever arm 16h may function through a point substantially on the center line C-11 indicated in FIGURE 4j. whereas a point of rotation indicated at C-X in FIGURE 4 may be involved in the central portion of the doctor back I2 and the positional relationship between this point of rotation C-X and Ithe line of contact L-11 is different from that of a point on the true central axis C-ll.

Referring now to FIGURES and `6, it will be seen that the instant invention involves an apparatus comprising a roll 2t) mounted for rotation, a doctor blade 2l urged Vinto cooperative relationship With said roll 2o and extending from substantially one end 2'lb of the roll Ztl' to the other end 20c, and a doctor back indicated generally by the reference numeral 22 ccextensive with the blade 21 and carrying the same. The doctor back 22 is here indicated as a box beam also provided with a forward lip 22a which actually mounts the doctor blade 2l in conventional manner. This is also indicated in FIG- URE l0, wherein the relationship `between the doctor blade leading edge 21a and the theoretical line of contact L-2I is showh generally along the lines of the prior art.

The doctor back 22 is here indicated as a hollow beam open at its ends and receiving a cross beam 23 coextensive therewith. The cross beam 23 may have any one of a number of suitable structures for supporting a load, but it is here indicated as a generally cylindrical member 23 with right and left hand ends 23C and 23h rotatably 'mounted in ixed bearings 24b and 245e respectively and provided with caps 25b and 25C mounting lever arms 26b and 26e extending outwardly to suitable adjustable positioning means 27h and 27C for rotating the cross beam 23 about a central axis C-23. The allochiral bear- 'ings24b and 24e rotatably mounting opposite ends of the cross beam 23 carries substantially the entire load thereof (which includes the weight of the cross beam, plus the entire load of the doctor back 22), and, although the mounting of the doctor back and the cross beam will be described next, it is apparent that rotation of the cross beam 23 via the lever arms 26h, 26C eifects movement of the 'doctor blade 21 toward and away from the operating surface 28 of 4the roll 20.

As shown in FIGURES 5 and 6, the doctor back 22 is provided with separate spaced resilient allochiral mounting means 3tlb and 30C positioned intermediate the central por-tion of the doctor back 22 and each of the ends 22h and 22C thereof for supporting the load of the doctor back 22 on the cross beam 23:. The blade 2i is substantially 'the center and each of the ends of the blade 21. Although the details of each of such mounting means Sill) will be described in detail in connection with FIGURE 9, it should be noted that (as shown in FIGURE 5) the left hand mounting element Btlb is positioned at approximately the left hand quarter point of the doctor back 22 and the right hand mounting means 30C is positioned at approximately the right hand quarter point of the doctor back 22. Also, as indicated in FIGURES -6 and l0, the left hand mounting means 30h has a symmetrical lower counterpart 31h positioned directly therebenea-th and in similar manner interposed between the doctor back 22 and the cross beam 23 so as to effect iirm mounting therebetween. In like manner, the right hand mounting means 30C is provided with a lower counterpart 31e for the same purpose. It will be appreciated that an important feature of the instant invention resides in the concept of positioning the left hand mounting means 39h-31h intermediate the doctor back (and blade) center and end 2217 (preferably the quarter point), and this upper and lower mounting means 30h- 31h may also consist of a continuous device completely surrounding the cross beam 23 at this location and securing 'the same to the side as well as the top and bottom adjacent portions of the doctor back 22 (although the cross section shape is preferably that shown in FIGURE 9 in such an arrangement).

The overall load of the doctor blade 21, doctor back 22 and cross beam 23 carried by the bearings 24b -and `24e will tend to resul-t in central beam deiiection in the cross beam 23, so that the central axis of the same will be deflected downwardly lfrom the true center line C-23, as shown in exaggerated manner .by the dashed line D-23 in FIGURE 6. If the doctor back 22 were, likewise, mounted solely at its .opposite ends, it would deflect downwardly in a similar manner at the central portion, such as is indicated -by the .dashed line D422 in FIGURE 7. In the practice of the invention, however, the doctor back 22 is not supported -at its ends and, instead, the load thereof is supported substantially entirely by the mounting means Silb and 30C which are positioned inwardly from the ends thereof in the manner already described. As indicated in FIGURE 7, this results in a center line (indicated by the doit-dash line X-ZZ) which deviates only slightly from the theoretical true center line C22. First of all, the distance between the two supporting means 30]; and 30C is much smaller than the distance between the bearings 24h and 24e, so the total beam deflection in the center cx is quite nominal, and ythere is only a relatively slight downward Ideflection -at the left and right hand edges b and c, whereas substantially the true center line C-22 is maintained at approximately the points of support Blob and 30C. The average deviation from the true center line C22 in the case of the line X-22 is only a small fraction (less than about 1A) of the average deflection obtained in the case of the same doctor back 22 supported at its ends (as in the case of the line `13-22). This affords a number of advantages in the practice of the invention in initially mounting the doctor blade 21 on the doctor back, since .the doctor back 22 does not have such a substantial ydeflection which must be compensated :for or corrected in the mounting of the doctor blade 21.

In addition, variations `in operating conditions do not effect as correspondingly great variation inthe doctor blade 2l mounting. For example, temperature changes in the doctor back 22 will not be reflected in changes in the deflection thereof (eg. corresponding to the changes from the line D-:Il to the-line T-Il in FIGURE 3). Also, the use of the lever larms 2611 and c to vary the relative positions and/or pressure between Ithe roll surface 20a and the leading edge 21a of the doctor blade 21 is also greatly simplied by the force arrangement here involved.

In this respect, it will be noted irst of all that the allochiral mounting means 3tlb and tlc are so positioned in substantially symmetrical relationship that, even though the cross ,beam 23 may have substantial deeotion, the axes of rotation in the region of the mounting means 3tb and 30o are substantially aligned and are positioned with respect to the line .of Contact L-2I in substantially the same manner ,(thereby eliminating a variable present in prior art operation). In addition, it will 4be appreciated that although the eifect of a substantial increase in the pressure at which the doctor blade 21 is urged against the roll surface 2da would in the prior art tend to load the doctor blade 21 and doctor 4back lip 22a so as to effect a central upward deliection indicated at U 2l in FIGURE 8, this extensive deflection (U-21) is substantially eliminated by the positioning of the mounting means 30h, 30C. It Will be appreciated that the force couple acting via the lever arms 26b and 26e is in turn exerted upon the doctor back lip 22a at the region of the mounting means 30h and 30C intermediate the ends of the doctor back 22 and, odi course, the doctor blade 21. This tends to impart to the doctor blade 2l a corrected center line indicated in dot-dash lines at X-21 in FIGURE 8, which conforms substantially with the Itheoretical or true center line C-2-1 in the region of the mounting means Etlb and 30e and which is deilected only slightly upwardly in the central portion of the doctor blade 21 and at the edges thereof. The differences between the lines X-2I and X-22 shown in FIGURES 7 and 8 and the deflection curves U-21 land D-22 shown in these same figures a-re very substantial from an operating point of View.

As indicated previously, the mounting means 30]), c and spaanse Sib, c are resilient means, and the cross-sectional configuration of each is comparable to that of the element Stlb shown in detail in FIGURE 9. It will be appreciated that the element Stic is substantially symmetrical in crosssection to the element Sill?, these being allochiral mates, land the element 3111 is symmetrical to the element 36h in cross-section.

As indicated in FIGURE 9, the mounting means ib comprises an upper block 40 Welded to the roof of the doctor back 22 and presenting a tapered arcuate face 40a.. The cross beam 23 also mounts a block 4i welded thereto which presents an opposed converging face 41a which has la matingly convex arcuate contour to conform with the concave arcuate contour of the upper face alla. A resilient sandwich indicated generally by the reference numeral 42 is Iforce-fit between the converging faces dilo and 41a. The sandwich structure 421 itself is slightly arcuate to conform with the contours of the surface 4th: and 41a and it comprises correspondingly arcuate tapered outer metallic elements 42a and 4211 vulcanized to a central rubber element 42e (or other solid elastomer). In assembling, the metallic blocks 40 and 4l are welded in place and the sandwich 42 is then force-fit into place and locked in position, for example, by stop blocks 43a and 3b secured to the doctor back 22 `and cross beam 23, respectively. The sandwich structure 42 may also be secured in position by means of a pin passing through suitable apertures therein and in the blocks #tti and 41 and perhaps the doctors back 22. The sandwich structure 42. is forced into position under sufiicient pressure to compress the arcuate rubber layer 42e in such a manner that the rubber layer 42C will be compressively loaded at all ltimes during operation of the device and will not be subject to tens-ion stresses or even to a neutral unloaded condition during operation. It is particularly advantageous to avoid relieving the rubber layer 42e from a precompressed condition at lany time during operation thereof in order to obtain effective operating life therefor.

It will be appreciated that the precompression of the rubber ylayer 42C is calculated so that this rubber layer 42C remains in compression during expansion and contraction of the `doctor back 42 and/ or cross beam 2.3 as a result of variations in operating temperatures. Also, the vibrations which are inherent in the operation of doctors will not be of sufficient magnitude to relieve the compression in the resilient rubber layer 42C. Likewise, the compression of the rubber layer 42C is of sufficient magnitude as a result of the force-tting of the sandwich 4.12 to maintain the same in compression during variations in the force couple applied through the lever arms 26h and 25e. The wedging of the sandwich 42, via stop elements 43a, 3b or other means is carried out in order to obtain the desired precompressed state of the rubber layer 42e at the time of assembly of the instant device.

The resulting resilient mounting means 30h, c, 31h, c (each of which has a precompressed rubber layer 42e or a substantial counterpart thereof) effects la distinctly superior damping of the vibration of the doctor blade transmitted to the doctor back and it also affords unique means for compensating for operating variables, lsuch as temperature changes and the like which may effect variations in the force relationship between the cross beam 23 and the doctor back 22. The function of the sandwich structure 42 comprising nested concentric deformable arcuate metal sleeve elements 42d and 42h and the conforming rubber element 42C in preloaded compressive stress of sufficient magnitude to accommodate relative deformations tand/:or shifting of the doctor back and cross beam without approaching a tension stress in the rubber thus functions not only `advantageously in damping vibration but also in responding to operation variables which may tend to interfere with the desired relationship between the leading edge of the `doctor blade 2id and the roll surface 20a.

It will be understood that modifications and variations S may be effected without departing from the spirit and scope of the novel concepts of the present invention, as :set forth -in the claims.

I claim as m-y invention: 1. In an assembly for mounting a doctor blade adapted to cooperate With a traveling surface, in combination, a

Y Adoctor back for carrying the doctor blade that is substantially coextensive therewith, a cross beam coextensive with said docto-r back, and allochiral mounting means positioned intermediate the central portion of said doctor blade and each of the ends thereof for supporting the load of said doctor back on said cross beam.

2.. In an assembly `for mounting a doctor blade adapted to cooperate with a traveling surface, in combination, a doctor back for carrying the `doctor blade that is subst-antially coextensive therewith, a cross beam coextensive with `said doctor back, and separate spaced resilient allochiral mounting means positioned intermediate the central portion of said doctor blade and each of the ends thereof for supporting the load of said doctor back on said cross beam.

3. In an assembly for mounting a doctor blade adapted to cooperate with a traveling surface, in combination, a doctor back for carrying the doctor blade that is substantial-ly coextensive therewith, a cross beam coextensive with said doctor back, means mounted at opposite ends of said cross beam for supporting the load thereof, and allochiral mounting means positioned intermediate the central portion of said doctor blade and each of the ends thereof for supporting the load of said doctor back on said 'cross beam. p

4. in yan assembly for mounting a doctor blade adapted to cooperate with a traveling surface, in combination, a doctor back for carrying the doctor blade that is substantially coextensive therewith, `a cross beam coextensive with said `doctor back, means mounted lat opposite ends of said cross beam for supporting the load thereof, means for rotating said cross beam, and separate sp-aced resilient allochiral mounting means positioned intermediate the 'central portion of said doctor blade and each of the ends thereof for supporting the load of said doctor back on said cross beam.

5. Apparatus comprising a roll mounted for rotation, a doctor blade urged into cooperative relationship with said roll and extending substantially from one end of the roll to the other, a doctor back coextensive with said blade and carrying the same, a cross beam received by said doctor back and coextensive therewith, mounting means positioned inwardly from the ends of said doctor blade at approximately the quarter points thereof carrying the load of the doctor back on said cross beam, said mounting means holding the doctor back and beam against relative rotation, means rotatably mounting the opposite ends of said cross beam and carrying the load thereof, and means for rotating said cross beam thereby to urge said doctor blade thus carried thereby against said roll.

6. Apparatus comprising a roll mounted for rotation, a doctor blade urged into cooperative relationship with said roll `and extending substantially from one end of the roll to the other, ra doctor back coextensive with said blade and carrying the same, a cross beam received by said doctor back and coextensive therewith, separate resilient allochiral mounting means positioned inwardly from the ends of said doctor blade at approximately the quarter points thereof carrying the load of the doctor back on said cross beam said mounting means holding the doctor back and beam against relative rotation, means rotatably mounting the opposite ends of said cross beam and carrying the load thereof, land means for rotating said cross beam thereby to urge said doctor blade thus carried thereby against said roll, said resilient mounting means effecting damping of vibration of said doctor back.

7. In an assembly for mounting a doctor blade adapted to cooperate with 1a traveling surface, in combination, a doctor back for carrying the doctor blade that is substantially coextensive therewith, a cross beam coextensive with said doctor back, allochiral sets of opposed receiving means mounted on said doctor back :and said cross bea-m intermediate the central portion of said doctor blade and each of its ends, said receiving means presenting converging opposed faces, and allochiral resilient mounting means urged between said converging faces for supporting the load of said doctor back on said cross beam.

8. In an assembly for mounting a doctor blade adapted to cooperate with a traveling surface, in combination, a doctor back for carrying the `doctor biade that is substantially coextensive therewith, a cross beam coextensive with said doctor back, allochiral sets of opposed receiving means mounted on said doctor back and said cross beam intermediate the central portion of said doctor blade and each of its ends, said receiving rneans presenting converging opposed faces, and allochiral resilient tapered laminated mounting assemblies urged 'between said converging faces for supporting the load o-f said doctor back on said cross beam.

9. In an assembly for mounting a doctor blade adapted to cooperate with :a traveling surface, in combination, a doctor back for carrying the doctor blade that is substantially coextensive therewith, ia cross beam coextensive with said doctor back, allochiral sets of opposed receiving means mounted on said doctor black and said cross beam intermediate the central portion of said doctor `blade 'and each of its ends, said receiving means presenting converging opposed faces, and allochiral resilient tapered laminated mounting assemblies urged between said converging faces for supporting the load of said doctor back on said cross beam, each of said assemblies comprising outer deformable meta-l walls and an internal solid elastomer ply that is maintained in precompressed condition under compressive stress of sufficient magnitude to accommodate relative deformations of the doctor back and cross beam without approaching a tension stress in any portion thereof.

10. In Ian assembly for mounting a doctor blade adapted to cooperate with `a traveling surface, in combination, a doctor back for carrying the doctor blade that is substantially coextensive therewith, a cross beam coextensive with said doctor back, and separate spaced resilient allochiral mounting means positioned intermediate the central portion of said doctor blade and each of the ends thereof for supporting the load of sai-d @doctor back on said cross beam, said mounting means comprising a solid elastomer layer that is maintained in precompressed condition under compressive stress of sufficient magnitude to accommodate relative deformations of the doctor back and cross beam without :approaching a tension stress in any portion thereof.

l1. In an assembly for mounting a doctor Ablade adapted to cooperate with a traveling surface, in combination, a Kdoctor back for carrying the doctor blade that is substantially coextensive therewith, a cross beam coextensive with said doctor back, allochiral sets of `opposed receiving -means mounted on said doctor back and said cross beam intermedi-ate the central portion of said doctor blade and each of its ends, -said receiving means presenting converging opposed faces, allochiral resilient mounting means urged between said converging faces for supporting the load of said `doctor back on said cross beam, and means maintaining -said resilient mounting means in precompressed state.

12. Apparatus comprising a roll mounted for rotation, a doc-tor blade urged into cooperative relationship with said roll and extending substantially from one end of the roll to the other, a doctor back coextensive with said blade and carrying the same, a cross beam received by said doctor back and coextensive therewith, allochiral sets of opposed receiving means mounted on said doctor back and said cross beam intermediate the central portion of said doctor blade and each of its ends, said receiving means presenting converging opposed faces, and allochiral resilient mounting means urged between said converging faces for supporting the load of said ldoctor back on said cross beam said Imounting means holding the doctor back and beam against relative rotation, means rotatably mounting the opposite ends of said cross beam and carrying the load thereof, land means for rotating said cross bea-m. thereby to u-rge said doctor blade thus carried thereby against said roll.

References Cited in the file of this patent UNITED STATES PATENTS 2,857,612 Fischer Oct. 28. 19'58 

1. IN AN ASSEMBLY FOR MOUNTING A DOCTOR BLADE ADAPTED TO COOPERATE WITH A TRAVELING SURFACE, IN COMBINATION, A DOCTOR BACK FOR CARRYING THE DOCTOR BLADE THAT IS SUBSTANTIALLY COEXTENSIVE THEREWITH, A CROSS BEAM COEXTENSIVE WITH SAID DOCTOR BACK, AND ALLOCHIRAL MOUNTING MEANS POSITIONED INTERMEDIATE THE CENTRAL PORTION OF SAID DOCTOR BLADE AND EACH OF THE ENDS THEREOF FOR SUPPORTING THE LOAD OF SAID DOCTOR BACK ON SAID CROSS BEAM. 